I'm not sure what you mean. Right now the owner of a house can sell a house and get cash, which is worth X dollars a month when invested. Or, they can choose

I'm not sure what you mean. Right now the owner of a house can sell a house and get cash, which is worth X dollars a month when invested. Or, they can choose to keep the house and rent it out. They will get Y dollars a month for rent, get Z dollars a month in appreciation, but pay P a month in taxes and maintenance. They will choose to rent out the house if Y+Z-P>X. If you double P (the property tax) then this equation becomes far less likely to be true. More people will sell their house to people looking to own a house, thus taking rental units off the market.